1. Field of the Invention
The present invention relates to methods and apparatus for obtaining images of a cornea, by which enlarged images of cornea cells such as cornea endothelium cells or cornea epithelium cells of an eyeball of a subject can be observed or photographed.
2. Description of the Prior Art
For seeing influences of contact lenses or for medical examination and treatment before and after an operation of cataract, it is necessary to observe the state of cornea endothelium cells. Therefore, for observation or photographing of cornea endothelium cells of an eyeball of a subject with their enlarged images, there have conventionally been used apparatus in which with an objective lens of a microscope of non-contact type or contact type with respect to the eyeball surface of the subject, slit illuminating light is applied toward an observation part obliquely of the eye axis and separated into reflected light from the cornea surface and image rays of light of endothelium cells so that an image of the cornea endothelium cells of the subject part are imaged by a TV camera or the like. Meanwhile, there has been proposed an ophthalmological apparatus equipped with a so-called alignment device for aligning the imaging center axis of the apparatus with the eye axis to make the TV camera focused on the subject part, such as disclosed in Japanese Patent Laid-Open Publication No. HEI 2-283352.
In these conventional apparatus, the focusing on the cornea endothelium has been accomplished in the following way. That is, the eye axis of the subject is aligned with the optical axis of the microscope (optical-axis adjustment) by manually moving a microscope frame, on which a TV camera is mounted, up and down or right and left with the use of an operation member such as a joy stick so that the alignment indicator light is located at the center of the pupil of the eye on a monitor screen. In this state, the frame, which is the main body, is moved back and forth also manually, so that the focusing is accomplished. As a result, substantial labors and skills have been required for the focusing on the cornea endothelium cells of the subject part. Further, in making observation or photographing with the above apparatus, there have been demands for observing or photographing not only the center part but also various sites of the cornea with their enlarged images, depending on what is examined in the medical treatment. However, only enlarged images of observation or photographing could hardly make it known which site of the cornea is shown.
Furthermore, these apparatus, although capable of observing or photographing the cornea endothelium, have been incapable of observing or photographing the cornea epithelium cells with their enlarged images, to a disadvantage.
In doing this, even if it is attempted that the slit illuminating light is applied toward the observation subject part obliquely of the eye axis so that the cornea epithelium cells of the subject part are imaged by a TV camera or the like with the reflected light from the cornea epithelium cells, reflected light from the cornea epithelium surface normally overlaps with reflected light from the lachrymal layer (including the mucin layer) that makes the epithelium surface normally wet, making it impossible to photograph enlarged images of the cornea epithelium cells. Still more, recently, there has been a desire for obtaining enlarged images of the cornea epithelium cells for use of examining aches of the cornea due to normal use of contact lenses.